Building off Augmented Image Tracking - Place a cube?

Hey all,

New AR dev trying to learn how to effectively place objects.

I’m working off of this:
It tracks one of several candidate images and puts a 3d frame around them. What I would like to do is remove the frame and place a basic cube out from the image. Ideal use case is that the tracked picture is on a computer screen, and the cube is placed outwards from the image toward the user. I tried replacing the “Spawn actor” function to use a cube actor, and removed the extra code to track to the image’s corners. However, no cube comes up. Any idea how I could easily and effectively do this?